/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */
bool isSameTree(struct TreeNode* p, struct TreeNode* q) 
{
    if(p==NULL&&q==NULL) return true;
    if(p==NULL||q==NULL) return false;
    if(p->val!=q->val) return false;
    return isSameTree(p->left,q->left)&&isSameTree(p->right,q->right);
}
